Buggy code:
class JThis extends This implements ActionListener , AdjustmentListener , ComponentListener , ContainerListener , FocusListener , ItemListener , KeyListener , MouseListener , MouseMotionListener , TextListener , WindowListener , PropertyChangeListener , AncestorListener , CaretListener , CellEditorListener , ChangeListener , DocumentListener , HyperlinkListener , InternalFrameListener , ListDataListener , ListSelectionListener , MenuDragMouseListener , MenuKeyListener , MenuListener , MouseInputListener , PopupMenuListener , TableColumnModelListener , TableModelListener , TreeExpansionListener , TreeModelListener , TreeSelectionListener , TreeWillExpandListener , UndoableEditListener { JThis ( NameSpace namespace , Interpreter declaringInterp ) { } public String toString ( ) { <START_BUG> return "'this'<seq2seq4repair_space>reference<seq2seq4repair_space>(JThis)<seq2seq4repair_space>to<seq2seq4repair_space>Bsh<seq2seq4repair_space>object:<seq2seq4repair_space>" + ( namespace . nsName ) ; <END_BUG> } void event ( String name , Object event ) { } public void ancestorAdded ( AncestorEvent e ) { } public void ancestorRemoved ( AncestorEvent e ) { } public void ancestorMoved ( AncestorEvent e ) { } public void caretUpdate ( CaretEvent e ) { } public void editingStopped ( ChangeEvent e ) { } public void editingCanceled ( ChangeEvent e ) { } public void stateChanged ( ChangeEvent e ) { } public void insertUpdate ( DocumentEvent e ) { } public void removeUpdate ( DocumentEvent e ) { } public void changedUpdate ( DocumentEvent e ) { } public void hyperlinkUpdate ( HyperlinkEvent e ) { } public void internalFrameOpened ( InternalFrameEvent e ) { } public void internalFrameClosing ( InternalFrameEvent e ) { } public void internalFrameClosed ( InternalFrameEvent e ) { } public void internalFrameIconified ( InternalFrameEvent e ) { } public void internalFrameDeiconified ( InternalFrameEvent e ) { } public void internalFrameActivated ( InternalFrameEvent e ) { } public void internalFrameDeactivated ( InternalFrameEvent e ) { } public void intervalAdded ( ListDataEvent e ) { } public void intervalRemoved ( ListDataEvent e ) { } public void contentsChanged ( ListDataEvent e ) { } public void valueChanged ( ListSelectionEvent e ) { } public void menuDragMouseEntered ( MenuDragMouseEvent e ) { } public void menuDragMouseExited ( MenuDragMouseEvent e ) { } public void menuDragMouseDragged ( MenuDragMouseEvent e ) { } public void menuDragMouseReleased ( MenuDragMouseEvent e ) { } public void menuKeyTyped ( MenuKeyEvent e ) { } public void menuKeyPressed ( MenuKeyEvent e ) { } public void menuKeyReleased ( MenuKeyEvent e ) { } public void menuSelected ( MenuEvent e ) { } public void menuDeselected ( MenuEvent e ) { } public void menuCanceled ( MenuEvent e ) { } public void popupMenuWillBecomeVisible ( PopupMenuEvent e ) { } public void popupMenuWillBecomeInvisible ( PopupMenuEvent e ) { } public void popupMenuCanceled ( PopupMenuEvent e ) { } public void columnAdded ( TableColumnModelEvent e ) { } public void columnRemoved ( TableColumnModelEvent e ) { } public void columnMoved ( TableColumnModelEvent e ) { } public void columnMarginChanged ( ChangeEvent e ) { } public void columnSelectionChanged ( ListSelectionEvent e ) { } public void tableChanged ( TableModelEvent e ) { } public void treeExpanded ( TreeExpansionEvent e ) { } public void treeCollapsed ( TreeExpansionEvent e ) { } public void treeNodesChanged ( TreeModelEvent e ) { } public void treeNodesInserted ( TreeModelEvent e ) { } public void treeNodesRemoved ( TreeModelEvent e ) { } public void treeStructureChanged ( TreeModelEvent e ) { } public void valueChanged ( TreeSelectionEvent e ) { } public void treeWillExpand ( TreeExpansionEvent e ) { } public void treeWillCollapse ( TreeExpansionEvent e ) { } public void undoableEditHappened ( UndoableEditEvent e ) { } public void actionPerformed ( ActionEvent e ) { } public void adjustmentValueChanged ( AdjustmentEvent e ) { } public void componentResized ( ComponentEvent e ) { } public void componentMoved ( ComponentEvent e ) { } public void componentShown ( ComponentEvent e ) { } public void componentHidden ( ComponentEvent e ) { } public void componentAdded ( ContainerEvent e ) { } public void componentRemoved ( ContainerEvent e ) { } public void focusGained ( FocusEvent e ) { } public void focusLost ( FocusEvent e ) { } public void itemStateChanged ( ItemEvent e ) { } public void keyTyped ( KeyEvent e ) { } public void keyPressed ( KeyEvent e ) { } public void keyReleased ( KeyEvent e ) { } public void mouseClicked ( MouseEvent e ) { } public void mousePressed ( MouseEvent e ) { } public void mouseReleased ( MouseEvent e ) { } public void mouseEntered ( MouseEvent e ) { } public void mouseExited ( MouseEvent e ) { } public void mouseDragged ( MouseEvent e ) { } public void mouseMoved ( MouseEvent e ) { } public void textValueChanged ( TextEvent e ) { } public void windowOpened ( WindowEvent e ) { } public void windowClosing ( WindowEvent e ) { } public void windowClosed ( WindowEvent e ) { } public void windowIconified ( WindowEvent e ) { } public void windowDeiconified ( WindowEvent e ) { } public void windowActivated ( WindowEvent e ) { } public void windowDeactivated ( WindowEvent e ) { } public void propertyChange ( PropertyChangeEvent e ) { } public void vetoableChange ( PropertyChangeEvent e ) { } public boolean imageUpdate ( Image img , int infoflags , int x , int y , int width , int height ) { } }

Fix:
return "'this'<seq2seq4repair_space>reference<seq2seq4repair_space>(JThis)<seq2seq4repair_space>to<seq2seq4repair_space>Bsh<seq2seq4repair_space>object:<seq2seq4repair_space>" + ( namespace . getName ( ) ) ;